Process of preparing adhesive sheets



I Patented Aug-29,1939 l i v F 2,170,949

,u u'rsn STATES PATENT OFFICE Willard 1; Morgan, 2:32p, ma, assignor w Sylvania Industrial Corporation, Frederick:- billfij. Va. ,'a corporation of Virginia KoDrawing. Application June 23, 1936, Serial N9. 86,808

13 Claims. (CI. 91-48) The invention relates to a composition of matexemplified in the following detailed disclosure, ter, especially one containing rubber. More parand the scope of the invention will be indicated in ticularly, it relates to an adhesive material and the claims. pertains to normally tacky, pressure adherent ad- I have found that the odor of rubber may be hesive sheets and to rubber adhesive compositions substantially eliminated or decreased to an un- B that may be utilized in the production thereof. objectionable degree by incorporating with a rub- The heretofore known rubber adhesives or ceber composition a quantity'of phthalic acid. Thus merits, however they may have been produced, 'by the use of a small quantity er such substance have been characterized by the more or less proin the adhesive, tapes and wrapping blanks havl0 nounced odor characteristic of rubber. This odor ing a rubber adhesive may be employed for the i0 is ascribed to the presence in the rubber of amino wrapping of tobacco and food products, as well compounds, and it has not beenpossible, heretoas'a large number of commercial and industrial tore, to produce an adhesive substantially free applications which were formerly closed to the therefrom. The presence of this disagreeable use of rubber adhesives on account of their obid odor renders rubber adhesives unsuitable for use jectionable odor. 16 ontapes and laminated wrapping blanks for the I have also found that a relatively non-viscous packing of tobacco and food products. rubber adhesive composition giving a thin, clear It has also been found impossible to obtain and transparent pressure-sensitive adhesive coatfrom the hitherto known pressure sensitive ading may be obtained by the addition, to suitable 2o hesive compositions a thin, clear and transparent rubber cement, of halogen substitution products 20 coating which is quite essential in making transof aliphatic ethers as solvents for the rubber and, parent adhesive tapes. Ethyl and methyl alcohols in particular, by the addition of di-halogen subare the only suitable solvents known which have stituted ethyl ether. the power of decreasing the viscosity of thick In the practice of the invention, the backing w ordinary rubber cements. These solvents, howmay consist of a flexible sheet or film, preferably 95 ever, partially coagulate or precipitate the rubof a non flbrous, homogeneous material, e. g. reber and give cloudy films or coatings. generated cellulose, cellulose esters, as nitrocellu- An object of the invention is to obviate the forelose and cellulose acetate; cellulose ethers, as going and like disadvantages characterizing the ethyl cellulose and benzyl cellulose; synthetic previous products. plastics, as polymerized vinyl resins; casein, gela- 30 A further object of the invention is to provide tin and the like. a pressure-adherent adhesive sheet or tape that is The above backing materials may have a moisnormally removable and reuseable, and charactureproofing composition applied to one or both terized by having on one surface a coating of a sides thereof and preferably only on the side op normally tacky, substantially odorless, rubber posite to that to which the adhesive is applied. 35 base adhesive composition. It is preferable, however, to apply a superficial It is also an object of the invention to provide coating of wax to the .side opposite to that to a composition of matter having a rubber as a. which the rubber adhesive is applied. Suchawax base which is substantially free from the odor coating wil P v the adhesive film from Stickcharacteristic of rubber. ing to the adjacent backing layer in a roll of the w An additional object of the invention is to proadhesive material. vide an adhesive composition having a, rubb as These materials are characterized in their prea base which is substantially free from the odor ferred form by being transparent, flexible, of relcharactristic of rubber; is transparent, and of a at vely h gh tensile Strength, and c p e of be- 4d relatively light color. ing produced in sheet form, having a thickness 46 Another object of the invention is to provide an as low as eight ten-thousandths f an inch. adhesive composition having a rubber as a base Such non-fibrous, homogeneous materials. prowhich is relatively non-viscous; is transparent, vide a statisfactory surface for the adhesive which and of a relatively light color. is so strongly bound thereto that the novel ad- Other objects of the invention will in part be hesive sheets are removable and reuseable. so obvious and will in part appear hereinafter. The composition may comprise a rubber, a resin The invention accordingly comprises a novel and a deodorizing ingredient comprising phthalic product possessing the characteristics, properties acid. For a composition having high transparand relation of constituents and an article having ency and light color, a pale crepe rubber of high II the elements and the relation of elements all as purity is utilized along with di-halogen substitutll 'ed ethyl ether as a solvent. Part or all of the pale crepe rubber may be replaced by other terms of natural rubber, reclaimed rubber orrubber latex. It may be mentioned that the selection of a rubber ispreferably made with regard to its odor, in view o! the fact that the more pronounced the odor, the larger the quantity of deodorizing ingredient required.

As a resin, use is preferably made of ester gum, but satisfactory results may be obtained with high grade gum dammar, cumar resin and rosin, these being referred to hereinafter collectively under the term resin.

If desired, a small amount of a solid inorganic material having a refractive index in visible light substantially oi the same degree as that of the rubber may be added to the composition above given. For example, there may be employed bolted magnesium carbonate up to about 5% by weight. The magnesium carbonate should be free of grit, silica or other solid particles which might reduce the transparency of the adhesive The crepe rubber, resin, deodorizing ingredient and optional ingredients as desired may be dispersed in a suitable medium such, for example, as gasoline, benzene or a mixture of gasoline and benzene with or without a small amount of di-halogen substituted ethyl ether.

By way of illustrating, but not by way of limiting the invention, the several solid ingredients of the novel adhesive composition herein'disclosed may be employed in the following proportions, given in parts by weight Pale crepe rubber Q. 00-70 Resin 25-35 Deodorizing ingredient 0.1-1

Gasoline 'zo-so Benze I v 20-25 bb' dichloroethylether 4-10 As examples of suitable compositions which may be prepared according to this invention, there may be given the following, the ingredients being in parts by weight:

I II III IV V VI Gssolina. 47 40 40 bb'dichloroethylether 3.2 8.7 8.2 2.9

The above solutions will be sumciently fluid to be readily applied to the backing material by known methods such, for example, as by passing a sheet or web .over a coating roll or under a doctor blade. The coated material may then be passed through a suitable drying chamber wherein the solvents are evaporated, preferably at an elevated temperature. The ireshly coated and dried material is then aged, preferably for- 24 hours.

In addition to its use in the production of adhesive tapes, the novel adhesive composition may be applied to any suitable backing for subsequent use as a mask or other adhesive sheet, or it may be utilized in; laminating sheet materials, in veneering, and in the fabrication 0! shoes, rugs and other articles 'manuiacture.

ent invention there have been provided novel compositions having improved 'and technically important properties which may be economically and easily prepared and used, and since certain changes may be made in the above mentioned products and different embodiments of the invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense. It is also to be understood that, in the claims, ingredients recited in the singular are intended to include compatible mixtures of such ingredients wherever the sense permits. v

Having described my invention, what I claim as new and desire'to secure by Letters Patent is:

l. A process of producing anodorlesspressuresensitive adhesive sheet material which comprises coating a flexible sheet material with a composition comprising rubber, a resin, and phthalic acid, in a suitable. solvent, and subsequently evapcrating the solvent. I

2. A process of producing an odorless pressuresensitive adhesive sheet materialwhich comprises coating a fiexible non-fibrous, cellulosic sheet with a composition comprising from about 60% to 70% pale crepe rubber, from 25% to 35% of a resin, and from about 0.1% to 1.0% of phthalic acid, in a suitable solvent, and then evaporating the solvent.

3. A process of producing a adhesive material which comprises coating a flexible, non-fibrous, cellulose sheet material with' a composition comprising pale crepe rubber, a resin, magnesium carbonate in a solvent mixture which comprises benzene, gasoline and di-halogen substituted ethyl ether, and evaporating the solvent.

4. A process 01 producing a pressure-sensitive adhesive material which comprises coating a flexible sheet of regenerated cellulose with a com- It will thus be seen that by means of the prespressure-sensitive position comprising palecreperubber and a resin,

sure-sensitive adhesive tape which comprises ap-v plying to a sheet of transparent regenerated cellulose a thin transparent film of a composition comprising pale crepe rubber, a resin and magnesium carbonate in' a solvent mixture comprising benzene, gasoline and bb' dichloroethylether, and evaporating the solvent.

7. A composition 01' matter, comprising rubber and a deodorant substance comprising phthalic acid, said composition being substantially free from the odor characteristic of rubber and ot the odor of the deodorant.

8. A composition of matter comprising rubber, and from about 0.1% to 1% by weight oi a deodorant substance comprising phthalic acid, said composition being substantially free from the odor characteristic 0! rubber and 01 theodcr oi the deodorant.

9. An adhesive composition comprising rubber, a resin, a solvent mixture containing benzene and gasoline and 1rom'about 0.1% to 1% by 78 m about 0.1% m 1% of a deodorant substance weight (based on the solids) or a deodorant substance comprising phthalic acid. said composition apart from the solvent being substantially iree from the odor characteristic of rubber and of the odor of the deodorant.

10. An adhesive composition comprising about 60% to 70% pale crepe rubber, about to oi a resin and irom about 0.1% to 1% of a deodorant substance comprising phthalic acid, said composition being substantially free from the odor" characteristic of rubber and of the odor of the deodorant. l

11. An adhesive composition comprising about to pale crepe rubber. about 25% to 35% oi a resin, 1% to 5% magnesium carbonate and comprising phthalic acid, said composition being substantially tree iron the odor characteristic 0! rubber and ot the odor of the deodorant.

12. An adhesive composition comprising pale crepe rubber, a resin, and a solvent mixture therefor containing a-substituted aliphatic ether and a deodorant substance comprising phthalic acid.

18. An adhesive composition comprising from about 60% to 70% pale crepe rubber and about 25% to 35% of a resin dissolved in a solvent mixture therefor containing asmall amount-oi a halsen substituted aliphatic ether.

WILLARD L. MORGAN. 

